Bast fibre is plant fibre collected from the phloem or bast surrounding the stem of certain dicotyledonous plants. It provides strength to the stem; some of the economically important bast fibres are obtained from herbs cultivated in agriculture, as for instance flax, hemp, or ramie, but bast fibres from wild plants, as stinging nettle, trees such as lime or linden and mulberry have been used in the past. Bast fibres are classified as soft fibres, are flexible. Fibres from monocotyledonous plants, called "leaf fibre", are classified as hard fibres and are stiff. Since the valuable fibres are located in the phloem, they must be separated from the xylem material, sometimes from the epidermis; the process for this is called retting, can be performed by micro-organisms either on land or in water, or by chemicals or by pectinolytic enzymes. In the phloem, bast fibres occur in bundles that are glued together by calcium ions. More intense retting separates the fibre bundles into elementary fibres, that can be several centimetres long.
Bast fibres have higher tensile strength than other kinds, are used in high-quality textiles, yarn, composite materials and burlap. An important property of bast fibres is that they contain a special structure, the fibre node, that represents a weak point, gives flexibility. Seed hairs, such as cotton, do not have nodes. Plants that have been used for bast fibre include flax, jute, kudzu, milkweed, okra, paper mulberry and roselle hemp. Bast fibres are processed for use in carpet, rope, traditional carpets, hessian or burlap, sacks, etc. Bast fibres are used in the non-woven and composite technology industries for the manufacturing of non-woven mats and carpets, composite boards as furniture materials, automobile door panels and headliners, etc. From prehistoric times through at least the early 20th century, bast shoes were woven from bast strips in the forest areas of Eastern Europe. Where no other source of tanbark was available, bast has been used for tanning leather. International Jute Study Group Bast Fibre cords in Viking ships Bast fibre production with hemp
Textile manufacture during the British Industrial Revolution
Textile manufacture during the Industrial Revolution in Britain was centred in south Lancashire and the towns on both sides of the Pennines. In Germany it was concentrated in the Wupper Valley, Ruhr Region and Upper Silesia, in Spain it was concentrated in Catalonia while in the United States it was in New England; the four key drivers of the Industrial Revolution were textile manufacturing, iron founding, steam power and cheap labour. Before the 18th century, the manufacture of cloth was performed by individual workers, in the premises in which they lived and goods were transported around the country by packhorses or by river navigations and contour-following canals, constructed in the early 18th century. In the mid-18th century, artisans were inventing ways to become more productive. Silk and fustian fabrics were being eclipsed by cotton which became the most important textile. Innovations in carding and spinning enabled by advances in cast iron technology resulted in the creation of larger spinning mules and water frames.
The machinery was housed in water-powered mills on streams. The need for more power stimulated the production of steam-powered beam engines, rotative mill engines transmitting the power to line shafts on each floor of the mill. Surplus power capacity encouraged the construction of more sophisticated power looms working in weaving sheds; the scale of production in the mill towns round Manchester created a need for a commercial structure. The technology was used in worsted mills in the West Riding of Yorkshire and elsewhere; the commencement of the Industrial Revolution is linked to a small number of innovations, made in the second half of the 18th century: Textiles – John Kay's 1733, Flying shuttle enabled cloth to be woven faster, of a greater width, for the process to be mechanised. Cotton spinning using Richard Arkwright's water frame, James Hargreaves's Spinning Jenny, Samuel Crompton's Spinning Mule; this was patented in 1769 and so came out of patent in 1783. The end of the patent was followed by the erection of many cotton mills.
Similar technology was subsequently applied to spinning worsted yarn for various textiles and flax for linen. Steam power – The improved steam engine invented by James Watt and patented in 1775 was mainly used for pumping out mines, for water supply systems and to a lesser extend to power air blast for blast furnaces, but from the 1780s was applied to power machines; this enabled rapid development of efficient semi-automated factories on a unimaginable scale in places where waterpower was not available or not steady throughout the seasons. Early steam engines had poor speed control, which caused thread breakage, limiting their use in operations like spinning. Iron industry – In the Iron industry, coke was applied to all stages of iron smelting, replacing charcoal; this had been achieved much earlier for lead and copper as well as for producing pig iron in a blast furnace, but the second stage in the production of bar iron depended on the use of potting and stamping or puddling. Using a steam engine to power blast air to blast furnaces made higher furnace temperatures possible, which allowed the use of more lime to tie up sulfur in coal or coke.
The steam engine overcame the shortage of water power for iron works. Iron production surged after the 1750s when steam engines were employed in iron works; these represent three'leading sectors', in which there were key innovations, which allowed the economic take off by which the Industrial Revolution is defined. This is not to belittle many other inventions in the textile industry. Without earlier ones, such as the spinning jenny and flying shuttle in the textile industry and the smelting of pig iron with coke, these achievements might have been impossible. Inventions such as the power loom and Richard Trevithick's high pressure steam engine were important in the growing industrialisation of Britain; the application of steam engines to powering cotton mills and ironworks enabled these to be built in places that were most convenient because other resources were available, rather than where there was water to power a watermill. Cotton is the world's most important natural fibre. In the year 2007, the global yield was 25 million tons from 35 million hectares cultivated in more than 50 countries.
Cultivating and Harvesting Preparatory Processes Spinning Weaving Finishing Before the 1760s, textile production was a cottage industry using flax and wool. A typical weaving family would own one hand loom, which would be operated by the man with help of a boy; the knowledge of textile production had existed for centuries. India had a textile industry; when raw cotton was exported to Europe it could be used to make fustian. Two systems had developed for spinning: the simple wheel, which used an intermittent process and the more refined, Saxony wheel which drove a differential spindle and flyer with a heck that guided the thread onto the bobbin, as a continuous process; this was satisfactory for use on hand looms, but neither of these wheels could produce enough thread for the looms after the invention by John Kay in 1734 of the flying shuttle, which made the loom twice as productive. Cloth production moved away from the cottage into manufactories; the first moves towards manufactories called mills were made in the spinning sector
Fiber or fibre is a natural or synthetic substance, longer than it is wide. Fibers are used in the manufacture of other materials; the strongest engineering materials incorporate fibers, for example carbon fiber and ultra-high-molecular-weight polyethylene. Synthetic fibers can be produced cheaply and in large amounts compared to natural fibers, but for clothing natural fibers can give some benefits, such as comfort, over their synthetic counterparts. Natural fibers develop or occur in the fiber shape, include those produced by plants and geological processes, they can be classified according to their origin: Vegetable fibers are based on arrangements of cellulose with lignin: examples include cotton, jute, ramie, sisal and banana. Plant fibers are employed in the manufacture of paper and textile, dietary fiber is an important component of human nutrition. Wood fiber, distinguished from vegetable fiber, is from tree sources. Forms include groundwood, thermomechanical pulp, bleached or unbleached kraft or sulfite pulps.
Kraft and sulfite refer to the type of pulping process used to remove the lignin bonding the original wood structure, thus freeing the fibers for use in paper and engineered wood products such as fiberboard. Animal fibers consist of particular proteins. Instances are silkworm silk, spider silk, catgut, sea silk and hair such as cashmere wool and angora, fur such as sheepskin, mink, beaver, etc. Mineral fibers include the asbestos group. Asbestos is the only occurring long mineral fiber. Six minerals have been classified as "asbestos" including chrysotile of the serpentine class and those belonging to the amphibole class: amosite, tremolite and actinolite. Short, fiber-like minerals include palygorskite. Biological fibers known as fibrous proteins or protein filaments consist of biologically relevant and biologically important proteins, mutations or other genetic defects can lead to severe diseases. Instances are collagen family of proteins, muscle proteins like actin, cell proteins like microtubules and many others, spider silk and hair etc.
Human-made or chemical fibers are fibers whose chemical composition and properties are modified during the manufacturing process. Man-made fibers consist of synthetic fibers. Semi-synthetic fibers are made from raw materials with long-chain polymer structure and are only modified and degraded by chemical processes, in contrast to synthetic fibers such as nylon or dacron, which the chemist synthesizes from low-molecular weight compounds by polymerization reactions; the earliest semi-synthetic fiber is rayon. Most semi-synthetic fibers are cellulose regenerated fibers. Cellulose fibers are a subset of man-made fibers, regenerated from natural cellulose; the cellulose comes from various sources: rayon from tree wood fiber, Modal from beech trees, bamboo fiber from bamboo, seacell from seaweed, etc. In the production of these fibers, the cellulose is reduced to a pure form as a viscous mass and formed into fibers by extrusion through spinnerets. Therefore, the manufacturing process leaves few characteristics distinctive of the natural source material in the finished products.
Some examples of this fiber type are: rayon bamboo fiber Lyocell, a brand of rayon Modal, using beech trees as input diacetate fiber triacetate fiber. Cellulose diacetate and -triacetate were classified under the term rayon, but are now considered distinct materials. Synthetic come from synthetic materials such as petrochemicals, unlike those man-made fibers derived from such natural substances as cellulose or protein. Fiber classification in reinforced plastics falls into two classes: short fibers known as discontinuous fibers, with a general aspect ratio between 20 and 60, long fibers known as continuous fibers, the general aspect ratio is between 200 and 500. Metallic fibers can be drawn from ductile metals such as copper, gold or silver and extruded or deposited from more brittle ones, such as nickel, aluminum or iron. See Stainless steel fibers. Carbon fibers are based on oxidized and via pyrolysis carbonized polymers like PAN, but the end product is pure carbon. Silicon carbide fibers, where the basic polymers are not hydrocarbons but polymers, where about 50% of the carbon atoms are replaced by silicon atoms, so-called poly-carbo-silanes.
The pyrolysis yields an amorphous silicon carbide, including other elements like oxygen, titanium, or aluminium, but with mechanical properties similar to those of carbon fibers. Fiberglass, made from specific glass, optical fiber, made from purified natural quartz, are man-made fibers that come from natural raw materials, silica fiber, made from sodium silicate and basalt fiber made from melted basalt. Mineral fibers can be strong because they are formed with a low number of surface defects, asbestos is a common one. Polymer fibers are a subset of man-made fibers, which are based on synthetic chemicals rather than arising from natural materials by a purely physical process; these fibers are made from: polyamide nylon PET or PBT polyester phenol-formaldehyde polyvinyl chloride fiber vinyon polyolefins olefin fiber acrylic polyesters, pure polyester PAN fibers are used to make carbon fiber by roasting them in a low oxygen enviro
The coconut tree is a member of the palm tree family and the only living species of the genus Cocos. The term "coconut" can refer to the whole coconut palm, the seed, or the fruit, which botanically is a drupe, not a nut; the term is derived from the 16th-century Portuguese and Spanish word coco meaning "head" or "skull" after the three indentations on the coconut shell that resemble facial features. Coconuts are known for their versatility of uses; the inner flesh of the mature seed forms a regular part of the diets of many people in the tropics and subtropics. Coconuts are distinct from other fruits because their endosperm contains a large quantity of clear liquid, called "coconut milk" in the literature, when immature, may be harvested for their potable "coconut water" called "coconut juice". Mature, ripe coconuts can be used as edible seeds, or processed for oil and plant milk from the flesh, charcoal from the hard shell, coir from the fibrous husk. Dried coconut flesh is called copra, the oil and milk derived from it are used in cooking – frying in particular – as well as in soaps and cosmetics.
The hard shells, fibrous husks and long pinnate leaves can be used as material to make a variety of products for furnishing and decorating. The coconut has cultural and religious significance in certain societies in India, where it is used in Hindu rituals; the name coconut derives from seafarers during the 16th and 17th century for its resemblance to a head.'Coco' and'coconut' came from 1521 encounters by Portuguese and Spanish explorers with Pacific islanders, with the coconut shell reminding them of a ghost or witch in Portuguese folklore called coco. The specific name nucifera is Latin for "nut-bearing". Literary evidence from the Ramayana and Sri Lankan chronicles indicates that the coconut was present in South Asia before the 1st century BCE. Another early mention of the coconut dates back to the "One Thousand and One Nights" story of Sinbad the Sailor. Thenga, its Tamil name, was used in the detailed description of coconut found in Itinerario by Ludovico di Varthema published in 1510 and in the Hortus Indicus Malabaricus.
Earlier, it was called nux indica, a name used by Marco Polo in 1280 while in Sumatra, taken from the Arabs who called it jawz hindī, translating to "Indian nut". In the earliest description of the coconut palm known, given by Cosmos of Alexandria in his Topographia Christiana written around 545, there is a reference to the argell tree and its drupe. In March 1521, a description of the coconut was given by Antonio Pigafetta writing in Italian and using the words "cocho"/"cochi", as recorded in his journal after the first European crossing of the Pacific Ocean during the Magellan circumnavigation and meeting the inhabitants of what would become known as Guam and the Philippines, he explained how at Guam "they eat coconuts" and that the natives there "anoint the body and the hair with coconut and beniseed oil". The American botanist Orator F. Cook was one of the earliest modern researchers to propose a hypothesis in 1901 on the location of the origin of Cocos nucifera based on its current worldwide distribution.
He hypothesized that the coconut originated in the Americas, based on his belief that American coconut populations predated European contact and because he considered pan-tropical distribution by ocean currents improbable. Thor Heyerdahl used this as one part of his 1950 hypothesis to support his theory that the Pacific Islanders originated as two migration streams from the Canadian Pacific coast to Hawaii, on to Tahiti and New Zealand in a series of hops, another migration of a bearded and more advanced "white race" from South America via sailing balsa-wood rafts. Physical and genetic evidence, have overwhelmingly proven that Pacific Islanders originated from the eastward branch of the expansion of Austronesian peoples from Island Southeast Asia and Taiwan using more sophisticated outrigger canoe technology, not from the Americas. Genetic studies have identified the center of origin of coconuts as being the region between Southwest Asia and Melanesia, where it shows greatest genetic diversity.
Their cultivation and spread was tied to the early migrations of the Austronesian peoples who carried coconuts as canoe plants to islands they settled. The similarities of the local names in the Austronesian region is cited as evidence that the plant originated in the region. For example, the Polynesian and Melanesian term niu. A study in 2011 identified two genetically differentiated subpopulations of coconuts, one originating from Island Southeast Asia and the other from the southern margins of the Indian subcontinent; the Pacific group is the only one to display clear genetic and phenotypic indications that they were domesticated. The distribution of the Pacific coconuts correspond to the regions settled by Austronesian voyagers indicating that its spread was the result of human introductions, it is most strikingly displayed in Madagascar, an island settled by Austronesian sailors at around 2000 to 1500 BP. The coconut populations in the island show genetic admixture between the two subpopulations indicating that Pacific coconuts were brought by the Austronesian settlers
Scutching is a step in the processing of cotton or the dressing of flax or hemp in preparation for spinning. The scutching process separates the impurities from the raw material, such as the seeds from raw cotton or the straw and woody stem from flax fibers. Scutching can be done by a machine known as a scutcher. Hand scutching of flax is done with a small iron scraper; the end products of scutching flax are the long flax fibers, short coarser fibers called tow, waste woody matter called shive. In the early days of the cotton industry the raw material was manually beaten with sticks after being placed on a mesh, a process known as willowing or batting, until the task was mechanised by the development of machines known as willowers. Scutching machines were introduced in the early 19th-century, processed the raw material into a continuous sheet of cotton wadding known as a lap. Before cotton is processed, it has to be cleaned of its seeds and other impurities, which, in the early days, was done by spreading the raw cotton on a mesh and beating it with sticks, a process known as willowing or batting.
A scutching machine for cotton was invented in 1797, but did not get much attention until it was introduced in the cotton mills of Manchester in 1808 or'09. By 1816, scutchers had been adopted; the scutching machine passes the cotton through a pair of rollers strikes it with iron or steel bars, called beaters. The turning beaters strike the cotton hard and knock the seeds out; this process is done over a series of parallel bars. At the same time, air is blown across the bars; the end result is a continuous sheet of cotton wadding known as a lap, ready for the next stage of the production process, known as carding. To scutch flax by hand, the scutching knife is scraped down with a sharp strike against the fibers while they hang vertically; the edge of the knife is scraped along the fibers to pull away pieces of the stalk. This is repeated until the flax is smooth and silky; when scutching was done by hand, people could scutch up to 15 pounds of flax in one day, depending on the quality of the flax, as coarser flax, harder flax, poorly retted flax takes longer to scutch.
Retting removes the pectins that bind the fibers to the stalk and each other, so under-retted flax is harder to separate from the stalk, gets damaged in the scutching process. Over-retting the flax causes the fibers to break; these broken fibres are called codilla. In the scutching process, some of the fiber is scutched away along with the stalk, a normal part of the process. Scutching is done several ways by machine. Scutching mills started in Ireland, were used there by 1850, at a time when hand scutching was still common in Continental Europe. Machine scutching, while cheaper, causes more waste than scutching by hand. One method of machine scutching is to crush the stalks between two metal rollers so that parts of the stalk can be separated. A modern scutching machine can process up to 500 kilograms of flax every hour, produces about 70 kg of flax fibers and 30 kg of tow. Older machines create more waste. Cotton gin Cotton mill Hand processing flax Preparing flax for spinning Heckling Linen production Notes Bibliography
Oxford University Press
Oxford University Press is the largest university press in the world, the second oldest after Cambridge University Press. It is a department of the University of Oxford and is governed by a group of 15 academics appointed by the vice-chancellor known as the delegates of the press, they are headed by the secretary to the delegates, who serves as OUP's chief executive and as its major representative on other university bodies. Oxford University has used a similar system to oversee OUP since the 17th century; the Press is located on opposite Somerville College, in the suburb Jericho. The Oxford University Press Museum is located on Oxford. Visits are led by a member of the archive staff. Displays include a 19th-century printing press, the OUP buildings, the printing and history of the Oxford Almanack, Alice in Wonderland and the Oxford English Dictionary; the university became involved in the print trade around 1480, grew into a major printer of Bibles, prayer books, scholarly works. OUP took on the project that became the Oxford English Dictionary in the late 19th century, expanded to meet the ever-rising costs of the work.
As a result, the last hundred years has seen Oxford publish children's books, school text books, journals, the World's Classics series, a range of English language teaching texts. Moves into international markets led to OUP opening its own offices outside the United Kingdom, beginning with New York City in 1896. With the advent of computer technology and harsh trading conditions, the Press's printing house at Oxford was closed in 1989, its former paper mill at Wolvercote was demolished in 2004. By contracting out its printing and binding operations, the modern OUP publishes some 6,000 new titles around the world each year; the first printer associated with Oxford University was Theoderic Rood. A business associate of William Caxton, Rood seems to have brought his own wooden printing press to Oxford from Cologne as a speculative venture, to have worked in the city between around 1480 and 1483; the first book printed in Oxford, in 1478, an edition of Rufinus's Expositio in symbolum apostolorum, was printed by another, printer.
Famously, this was mis-dated in Roman numerals as "1468", thus pre-dating Caxton. Rood's printing included John Ankywyll's Compendium totius grammaticae, which set new standards for teaching of Latin grammar. After Rood, printing connected with the university remained sporadic for over half a century. Records or surviving work are few, Oxford did not put its printing on a firm footing until the 1580s. In response to constraints on printing outside London imposed by the Crown and the Stationers' Company, Oxford petitioned Elizabeth I of England for the formal right to operate a press at the university; the chancellor, Robert Dudley, 1st Earl of Leicester, pleaded Oxford's case. Some royal assent was obtained, since the printer Joseph Barnes began work, a decree of Star Chamber noted the legal existence of a press at "the universitie of Oxforde" in 1586. Oxford's chancellor, Archbishop William Laud, consolidated the legal status of the university's printing in the 1630s. Laud envisaged a unified press of world repute.
Oxford would establish it on university property, govern its operations, employ its staff, determine its printed work, benefit from its proceeds. To that end, he petitioned Charles I for rights that would enable Oxford to compete with the Stationers' Company and the King's Printer, obtained a succession of royal grants to aid it; these were brought together in Oxford's "Great Charter" in 1636, which gave the university the right to print "all manner of books". Laud obtained the "privilege" from the Crown of printing the King James or Authorized Version of Scripture at Oxford; this "privilege" created substantial returns in the next 250 years, although it was held in abeyance. The Stationers' Company was alarmed by the threat to its trade and lost little time in establishing a "Covenant of Forbearance" with Oxford. Under this, the Stationers paid an annual rent for the university not to exercise its full printing rights – money Oxford used to purchase new printing equipment for smaller purposes.
Laud made progress with internal organization of the Press. Besides establishing the system of Delegates, he created the wide-ranging supervisory post of "Architypographus": an academic who would have responsibility for every function of the business, from print shop management to proofreading; the post was more an ideal than a workable reality, but it survived in the loosely structured Press until the 18th century. In practice, Oxford's Warehouse-Keeper dealt with sales and the hiring and firing of print shop staff. Laud's plans, hit terrible obstacles, both personal and political. Falling foul of political intrigue, he was executed in 1645, by which time the English Civil War had broken out. Oxford became a Royalist stronghold during the conflict, many printers in the city concentrated on producing political pamphlets or sermons; some outstanding mathematical and Orientalist works emerged at this time—notably, texts edited by Edward Pococke, the Regius Professor of Hebrew—but no university press on Laud's model was possible before the Restoration of the Monarchy in 1660.
It was established by the vice-chancellor, John Fell, Dean of Christ Church, Bishop of Oxford, Secretary to the Delegates. Fell regarded Laud as a martyr, was determined to honour his vision of the Press. Using the provisions of the Great Charter, Fell persuaded Oxford to refuse any further payments from the Stationers and drew
Pectin is a structural heteropolysaccharide contained in the primary cell walls of terrestrial plants. It was first described in 1825 by Henri Braconnot, it is produced commercially as a white to light brown powder extracted from citrus fruits, is used in food as a gelling agent in jams and jellies. It is used in dessert fillings, sweets, as a stabilizer in fruit juices and milk drinks, as a source of dietary fiber. In plant biology, pectin consists of a complex set of polysaccharides that are present in most primary cell walls and are abundant in the non-woody parts of terrestrial plants. Pectin is a major component of the middle lamella, where it helps to bind cells together, but is found in primary cell walls. Pectin is deposited by exocytosis into the cell wall via vesicles produced in the golgi; the amount and chemical composition of pectin differs among plants, within a plant over time, in various parts of a plant. Pectin is an important cell wall polysaccharide that allows primary cell wall extension and plant growth.
During fruit ripening, pectin is broken down by the enzymes pectinase and pectinesterase, in which process the fruit becomes softer as the middle lamellae break down and cells become separated from each other. A similar process of cell separation caused by the breakdown of pectin occurs in the abscission zone of the petioles of deciduous plants at leaf fall. Pectin is a natural part of the human diet, but does not contribute to nutrition; the daily intake of pectin from fruits and vegetables can be estimated to be around 5 g if 500 g of fruits and vegetables are consumed per day. In human digestion, pectin binds to cholesterol in the gastrointestinal tract and slows glucose absorption by trapping carbohydrates. Pectin is thus a soluble dietary fiber. In non-obese diabetic mice pectin has been shown to increase the incidence of diabetes. A study found that after consumption of fruit the concentration of methanol in the human body increased by as much as an order of magnitude due to the degradation of natural pectin in the colon).
Pectin has been observed to have some function in repair the DNA of some types of plant seeds desert plants. Pectinaceous surface pellicles, which are rich in pectin, create a mucilage layer that holds in dew that helps the cell repair its DNA. Consumption of pectin has been shown to reduce blood LDL cholesterol levels; the effect depends upon the source of pectin. The mechanism appears to be an increase of viscosity in the intestinal tract, leading to a reduced absorption of cholesterol from bile or food. In the large intestine and colon, microorganisms degrade pectin and liberate short-chain fatty acids that have positive influence on health. Pectins known as pectic polysaccharides, are rich in galacturonic acid. Several distinct polysaccharides have been characterised within the pectic group. Homogalacturonans are linear chains of α--linked D-galacturonic acid. Substituted galacturonans are characterized by the presence of saccharide appendant residues branching from a backbone of D-galacturonic acid residues.
Rhamnogalacturonan I pectins contain a backbone of the repeating disaccharide: 4)-α-D-galacturonic acid--α-L-rhamnose-(1. From many of the rhamnose residues, sidechains of various neutral sugars branch off; the neutral sugars are D-galactose, L-arabinose and D-xylose, with the types and proportions of neutral sugars varying with the origin of pectin. Another structural type of pectin is rhamnogalacturonan II, a less frequent, complex branched polysaccharide. Rhamnogalacturonan II is classified by some authors within the group of substituted galacturonans since the rhamnogalacturonan II backbone is made of D-galacturonic acid units. Isolated pectin has a molecular weight of 60,000–130,000 g/mol, varying with origin and extraction conditions. In nature, around 80 percent of carboxyl groups of galacturonic acid are esterified with methanol; this proportion is decreased to a varying degree during pectin extraction. The ratio of esterified to non-esterified galacturonic acid determines the behavior of pectin in food applications.
This is why pectins are classified as high- vs. low-ester pectins, with more or less than half of all the galacturonic acid esterified. The non-esterified galacturonic acid units can be either free acids or salts with sodium, potassium, or calcium; the salts of esterified pectins are called pectinates, if the degree of esterification is below 5 percent the salts are called pectates, the insoluble acid form, pectic acid. Some plants, such as sugar beet and pears, contain pectins with acetylated galacturonic acid in addition to methyl esters. Acetylation increases the stabilising and emulsifying effects of pectin. Amidated pectin is a modified form of pectin. Here, some of the galacturonic acid is converted with ammonia to carboxylic acid amide; these pectins are more tolerant of varying calcium concentrations. To prepare a pectin-gel, the ingredients are heated. Upon cooling below gelling temperature, a gel starts to form. If gel formation is too strong, syneresis or a granular texture are the result, while weak gelling leads to excessively soft gels.
Pectins gel according to specific parameters, such as pH and bivalent salts. In hi